Common weed killer linked to bee deaths

The world's most widely used weed killer may also be indirectly killing bees. New research from The University of Texas at Austin shows that honey bees exposed to glyphosate, the active ingredient in Roundup, lose some of the beneficial bacteria in their guts and are more susceptible to infection and death from harmful bacteria.

Scientists believe this is evidence that glyphosate might be contributing to the decline of honey bees and native bees around the world.

Guidelines - Glyphosate - Use - Bee - Exposure

"We need better guidelines for glyphosate use, especially regarding bee exposure, because right now the guidelines assume bees are not harmed by the herbicide," said Erick Motta, the graduate student who led the research, along with professor Nancy Moran. "Our study shows that's not true."

The findings are published this week in the journal Proceedings of the National Academy of Sciences.

Glyphosate - Interferes - Enzyme - Plants - Microorganisms

Because glyphosate interferes with an important enzyme found in plants and microorganisms, but not in animals, it has long been assumed to be nontoxic to animals, including humans and bees. But this latest study shows that by altering a bee's gut microbiome—the ecosystem of bacteria living in the bee's digestive tract, including those that protect it from harmful bacteria—glyphosate compromises its ability to fight infection.

The researchers exposed honey bees to glyphosate at levels known to occur in crop fields, yards and roadsides. The researchers painted the bees' backs with colored dots so they could be tracked and later recaptured. Three days later, they observed that the herbicide significantly reduced healthy gut microbiota. Of eight dominant species of healthy bacteria in the exposed bees, four were found to be less abundant. The hardest hit bacterial species, Snodgrassella alvi, is a critical microbe that helps...